I remember learning this trick half a dozen of years ago, when I was doing the first steps towards digital art. I saw it in an open canvas event file I downloaded somewhere and I found it really interesting. Sadly that didn't work that well on photoshop so I stopped using it. But somewhere between the versions Adobe worked on his Linear Dodge blending mode and it's vaguely good now!
By the way, if you use OpenCanvas or paint tools SAI you're luckier, it works better there!
it works on Photoshop, Painter, paint tool SAI, Open Canvas for sure. Tell me if you try it on other software! Works great on the GIMP too![/edit]
great for digital colouring
font used: it's really good, take it!
pics that used this trick: